In recent years, the LED is frequently used for the light source of the illumination device. In the illumination device using the LED, one of the methods of obtaining white light is a method that uses three types of LEDs, a red LED, a blue LED, and a green LED.
However, the manufacturing cost increases with such a method since three types of LED element are required. Thus, an illumination device capable of irradiating white light with one type of LED element has been developed.
FIGS. 8A and 8B are schematic views showing one example of an LED illumination device disclosed in Patent Document 1 listed below, where FIG. 8A shows a front view and FIG. 8B shows a partially cutout plan view.
A conventional illumination device 101 shown in FIGS. 8A and 8B has a rotation plate 102 arranged above an LED element (light emitting element) 105. The rotation plate 102 has a plurality of circular through-holes radially arranged at equal intervals, and fluorescent-substance sheets 103 having different colors are each fitted into the through-holes. In the example of Patent Document 1, blue, green, yellow, orange, and red fluorescent-substance sheets are provided.
The rotation plate 102 has one portion projecting out to an outer side of a case 106 so as to be manually rotated by a user. The rotation plate 102 is configured to be rotatable by 360° in both clockwise and counterclockwise directions with a shaft 104 as a center.
When the rotation plate 102 is rotated, a relative positional relationship between the LED element 105 and each fluorescent-substance sheet 103 changes, so that the color temperature of the light irradiated from the illumination device can be changed in a stepless manner in the order of “daylight color”→“neutral white color”→“incandescent lamp color” or in the reverse order.